In the use of photocopiers, it is a common problem that a person making copies will pick up the copies but leave behind in the photocopier the original document from which the copies were made. In a large organization, or a situation where the photocopier may be used by persons in unrelated organizations, this not only may result in the loss of a valuable original document, but it produces a security risk for information in the document as well. While this problem usually occurs when documents are placed on the platen of a photocopier sheet-by-sheet, rather than when an automatic document feeder (“ADF”) is used, an original document may also be left in an ADF. In addition, this problem sometimes occurs in the-use of facsimile machines, which copy a document to a remote location. Both photocopiers and facsimile machines may be thought of as “document copiers.”
A number of different approaches to preventing persons using a photocopier from leaving original documents in the photocopier are known which rely on the use of some type of device for detecting the presence of an original document in the photocopier. The photocopier may simply provide a display panel which instructs the user to remove the original when copying is complete and the presence of the original is detected. Another approach is to provide an audio or visual alarm when the power switch of the photocopier is turned off while the original is still present. Alternatively, if the original is still present for a predetermined period of time after a copy has been made, the photocopier may sound an alarm. Yet another known approach is to detect whether an original is present after copying and also to detect whether the user has moved out of a predetermined range of the photocopier, in which case an alarm is sounded.
However, none of these approaches is believed to be adequate, as it is always possible for a distracted user to remove copies from the photocopier and leave the original behind. Similarly, none of these approaches necessarily prevents a person from leaving an original document in a facsimile machine after the document has been transmitted.